Barnard's Star d
Planet· orbits Barnard's Star
Barnard's Star d — the innermost and hottest of the four (equilibrium temperature ~480 K), a sub-Earth on a 2.34-day orbit. Never imaged; appearance unknown.
Open in 3D viewSee Barnard's Star d in the live, interactive 3D map
Key facts
Minimum mass
1.57 × 10²⁴ kg
0.263 M⊕
Year
2.34 Earth days
Distance from Barnard's Star
2,812,440 km
Science
Physical
- Minimum mass (m·sin i)
- 1.57 × 10²⁴ kg · 0.263 M⊕
- Radial-velocity detection measures m·sin i; the true mass depends on the unknown orbital inclination.
- Radius
- Not measured
- No transit — radius is a model estimate; true size unknown.
Orbital
- Semi-major axis
- 2,812,440 km
- From the NASA Exoplanet Archive (ESO/ESPRESSO radial-velocity orbit)
- Eccentricity
- 0.04
- From the NASA Exoplanet Archive (ESO/ESPRESSO radial-velocity orbit)
- Inclination
- 0.00 °
- From the NASA Exoplanet Archive (ESO/ESPRESSO radial-velocity orbit)
- Orbital period
- 2.3 days
- From the NASA Exoplanet Archive (ESO/ESPRESSO radial-velocity orbit)
- Perihelion
- 2,699,942 km
- Computed from the orbital elements
- Aphelion
- 2,924,938 km
- Computed from the orbital elements
- Mean orbital velocity
- 87.4 km/s
- Computed from the orbital elements
Composition
- Bulk composition
- Presumed rocky (minimum mass ~0.26 Earth); never imaged.
- Surface appearance
- Appearance based on ESO/M. Kornmesser's artist's concept. No spacecraft has imaged this world, so its real appearance is unknown — The surface shown is an artistic representation, shown only in Visual mode; Realism shows a plain spectral colour.
Radiation & temperature
- Insolation
- 9.9 S⊕ · 9.9× the sunlight Earth receives
- Computed from Barnard's Star's luminosity and the orbital distance (inverse-square; Earth's sunlight = 1).
- Equilibrium temperature
- 483 K (210 °C)
- Computed model value (no atmosphere assumed), the hottest of the four — not measured.
Discovery & history
- Method
- Radial-velocity detection (stellar wobble)
- Name
- Designated 'd' as the third planet found around Barnard's Star, following the IAU convention of lettering planets in discovery order starting at 'b'.
Part of the four-planet family established from ESO/ESPRESSO data in 2025 — the closest to the star, and the hottest.
Images
Never imaged — this world is known only from the tiny gravitational tug it exerts on its star (radial velocity). An artist's impression of the whole system is on the system view; the planet's own appearance is unknown.